Unaspirated ( Concept )
http://purl.org/linguistics/gold/Unaspirated

Unaspirated refers to the configuration of glottal opening, release at the oral stricture, and vocal fold vibration in which the glottal opening gesture begins at the moment that the oral closure is made, but the maximum width of the glottal opening is reached at about the mid-point of the oral closure duration and the vocal folds return to a voicing position at about the moment of release. This typically results in a weak sounding release which lacks the burst of air characteristic of aspirated phonemes. [Ladefoged and Maddieson 1996: 66-70]